The invention relates to automobile engine mounts, especially those that utilize both hydraulic fluid and elastomeric material as a vibration cushioning medium.
U.S. Pat. No. 3,387,839 relates to a duplex-type bushing which has three successively larger metal sleeves between which are a pair of solid rubber inserts to provide the needed resiliency for the bushing which can be adapted to an engine mount.
U.S. Pat. Nos. 3,642,268 and 4,702,346 and 4,834,351 are typical of the many patents which rely on a single rubber insert with separated cavities between which fluid, such as ethylene glycol solution, is free to circulate.
U.S. Pat. No. 4,840,357 covers a very complex dual elastomeric structure which is composed of two elastomeric inserts which are not in radially spaced relation, but which employs a dampening liquid which is free to circulate between voids or cavities formed in and between the two inserts.
U.S. Pat. No. 4,768,760 utilizes two radially spaced elastomeric inserts with specially shaped fluid containing cavities which are formed in the radially outermost insert and connected by fluid passageways in the radially innermost insert. Thus, both inserts are effected by the dampening fluid. The invention is directed to an improved engine mount which employs a combination of elastomeric inserts and dampening fluid which is different from anything shown in the prior art.
Briefly stated, the invention is in an engine mount which essentially comprises three successively larger metal sleeves between which are a pair of resilient, annular elastomeric inserts of springs. The larger, radially outermost insert is provided with a pair of spaced cavities with at least one connecting passageway through which a dampening fluid can flow freely between the cavities.
The invention is designed to combine the most desirable vibration control features of the common fluid mount and the mount which employs two resilient elastomeric springs.